/* ========================================
   Nexus Pittsburgh — Stylesheet
   ======================================== */

/* --- Reset & Base --- */
*, *::before, *::after {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

:root {
  --black: #0a0a0a;
  --white: #fafafa;
  --yellow: #f5c518;
  --yellow-light: #fde68a;
  --gray-100: #f4f4f5;
  --gray-200: #e4e4e7;
  --gray-400: #a1a1aa;
  --gray-600: #52525b;
  --gray-800: #27272a;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --max-width: 1120px;
  --section-padding: 120px 24px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: var(--font-sans);
  background: var(--black);
  color: var(--white);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  overflow-x: hidden;
}

a {
  color: inherit;
  text-decoration: none;
}

img {
  max-width: 100%;
  display: block;
}

/* --- Typography --- */
h1, h2, h3, h4 {
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -0.02em;
}

h1 {
  font-size: clamp(3rem, 8vw, 6rem);
}

h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  margin-bottom: 24px;
}

h3 {
  font-size: 1.25rem;
  margin-bottom: 12px;
}

p {
  color: var(--gray-400);
  font-size: 1.125rem;
  line-height: 1.7;
}

.section-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 600;
  letter-spacing: 0.15em;
  text-transform: uppercase;
  color: var(--yellow);
  margin-bottom: 16px;
}

/* --- Layout --- */
.container {
  max-width: var(--max-width);
  margin: 0 auto;
  width: 100%;
}

section {
  padding: var(--section-padding);
}

/* --- Navigation --- */
.nav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  padding: 20px 24px;
  transition: background var(--transition), box-shadow var(--transition);
}

.nav.scrolled {
  background: rgba(10, 10, 10, 0.9);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  box-shadow: 0 1px 0 rgba(255, 255, 255, 0.06);
}

.nav .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.nav-logo {
  font-size: 1.125rem;
  font-weight: 700;
  letter-spacing: -0.02em;
}

.nav-logo span {
  color: var(--yellow);
}

.nav-links {
  display: flex;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--gray-400);
  transition: color var(--transition);
}

.nav-links a:hover {
  color: var(--white);
}

.nav-cta {
  font-size: 0.875rem;
  font-weight: 600;
  padding: 10px 24px;
  background: var(--yellow);
  color: var(--black);
  border-radius: 8px;
  transition: opacity var(--transition), transform var(--transition);
}

.nav-cta:hover {
  opacity: 0.9;
  transform: translateY(-1px);
}

.nav-toggle {
  display: none;
  background: none;
  border: none;
  cursor: pointer;
  padding: 4px;
}

.nav-toggle span {
  display: block;
  width: 24px;
  height: 2px;
  background: var(--white);
  margin: 6px 0;
  transition: var(--transition);
}

/* --- Hero --- */
.hero {
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  padding: 160px 24px 120px;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: -40%;
  left: 50%;
  transform: translateX(-50%);
  width: 800px;
  height: 800px;
  background: radial-gradient(circle, rgba(245, 197, 24, 0.08) 0%, transparent 70%);
  pointer-events: none;
}

.hero-content {
  position: relative;
  z-index: 1;
  max-width: 800px;
}

.hero h1 {
  margin-bottom: 24px;
}

.hero h1 .accent {
  color: var(--yellow);
}

.hero p {
  font-size: clamp(1.125rem, 2vw, 1.375rem);
  max-width: 600px;
  margin: 0 auto 48px;
}

.hero-actions {
  display: flex;
  gap: 16px;
  justify-content: center;
  flex-wrap: wrap;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 16px 32px;
  background: var(--yellow);
  color: var(--black);
  font-size: 1rem;
  font-weight: 600;
  border-radius: 10px;
  border: none;
  cursor: pointer;
  transition: opacity var(--transition), transform var(--transition);
}

.btn-primary:hover {
  opacity: 0.9;
  transform: translateY(-2px);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 16px 32px;
  background: transparent;
  color: var(--white);
  font-size: 1rem;
  font-weight: 600;
  border-radius: 10px;
  border: 1px solid var(--gray-600);
  cursor: pointer;
  transition: border-color var(--transition), transform var(--transition);
}

.btn-secondary:hover {
  border-color: var(--gray-400);
  transform: translateY(-2px);
}

.hero-scroll {
  position: absolute;
  bottom: 40px;
  left: 50%;
  transform: translateX(-50%);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 8px;
  color: var(--gray-600);
  font-size: 0.75rem;
  letter-spacing: 0.1em;
  text-transform: uppercase;
  animation: bounce 2s infinite;
}

.hero-scroll .arrow {
  width: 1px;
  height: 32px;
  background: linear-gradient(to bottom, var(--gray-600), transparent);
}

@keyframes bounce {
  0%, 100% { transform: translateX(-50%) translateY(0); }
  50% { transform: translateX(-50%) translateY(8px); }
}

/* --- What Section --- */
.what {
  background: var(--black);
  border-top: 1px solid rgba(255,255,255,0.04);
}

.what .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 80px;
  align-items: center;
}

.what-text p {
  margin-bottom: 20px;
}

.what-visual {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.what-card {
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 16px;
  padding: 28px 24px;
  transition: border-color var(--transition), transform var(--transition);
}

.what-card:hover {
  border-color: rgba(245, 197, 24, 0.3);
  transform: translateY(-4px);
}

.what-card .icon {
  font-size: 1.75rem;
  margin-bottom: 16px;
}

.what-card h3 {
  font-size: 1rem;
  margin-bottom: 8px;
  color: var(--white);
}

.what-card p {
  font-size: 0.875rem;
  color: var(--gray-400);
  line-height: 1.5;
}

/* --- Why Section --- */
.why {
  background: var(--gray-800);
  position: relative;
}

.why .container {
  text-align: center;
}

.why > .container > p {
  max-width: 640px;
  margin: 0 auto 64px;
}

.why-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 32px;
  text-align: left;
}

.why-item {
  padding: 36px;
  background: rgba(255,255,255,0.03);
  border-radius: 16px;
  border: 1px solid rgba(255,255,255,0.06);
  transition: border-color var(--transition);
}

.why-item:hover {
  border-color: rgba(245, 197, 24, 0.25);
}

.why-item .number {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  font-size: 0.875rem;
  font-weight: 700;
  color: var(--black);
  background: var(--yellow);
  border-radius: 8px;
  margin-bottom: 20px;
}

.why-item h3 {
  color: var(--white);
}

.why-item p {
  font-size: 0.9375rem;
}

/* --- Who Section --- */
.who {
  background: var(--black);
  border-top: 1px solid rgba(255,255,255,0.04);
}

.who .container {
  text-align: center;
}

.who > .container > p {
  max-width: 560px;
  margin: 0 auto 64px;
}

.who-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  max-width: 720px;
  margin: 0 auto;
}

.who-tag {
  padding: 14px 28px;
  background: rgba(255,255,255,0.04);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 100px;
  font-size: 1rem;
  font-weight: 500;
  color: var(--gray-200);
  transition: var(--transition);
}

.who-tag:hover {
  background: rgba(245, 197, 24, 0.1);
  border-color: rgba(245, 197, 24, 0.3);
  color: var(--yellow);
}

/* --- How Section --- */
.how {
  background: var(--gray-800);
}

.how .container {
  text-align: center;
}

.how > .container > p {
  max-width: 560px;
  margin: 0 auto 64px;
}

.how-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  text-align: left;
}

.how-card {
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 16px;
  padding: 36px 28px;
  transition: border-color var(--transition), transform var(--transition);
}

.how-card:hover {
  border-color: rgba(245, 197, 24, 0.3);
  transform: translateY(-4px);
}

.how-card .icon {
  font-size: 2rem;
  margin-bottom: 20px;
}

.how-card h3 {
  color: var(--white);
  margin-bottom: 10px;
}

.how-card p {
  font-size: 0.9375rem;
}

/* --- Momentum Section --- */
.momentum {
  background: var(--black);
  border-top: 1px solid rgba(255,255,255,0.04);
  overflow: hidden;
}

.momentum .container {
  text-align: center;
}

.momentum > .container > p {
  max-width: 560px;
  margin: 0 auto 64px;
}

.stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  margin-bottom: 64px;
}

.stat {
  padding: 32px 16px;
}

.stat .number {
  font-size: clamp(2.5rem, 5vw, 3.5rem);
  font-weight: 800;
  color: var(--yellow);
  letter-spacing: -0.03em;
  line-height: 1;
  margin-bottom: 8px;
}

.stat .label {
  font-size: 0.875rem;
  color: var(--gray-400);
  font-weight: 500;
}

.testimonials {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  text-align: left;
}

.testimonial {
  background: rgba(255,255,255,0.03);
  border: 1px solid rgba(255,255,255,0.06);
  border-radius: 16px;
  padding: 32px;
}

.testimonial blockquote {
  font-size: 1rem;
  color: var(--gray-200);
  line-height: 1.6;
  margin-bottom: 20px;
  font-style: italic;
}

.testimonial .author {
  display: flex;
  align-items: center;
  gap: 12px;
}

.testimonial .avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gray-600);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-size: 0.875rem;
  color: var(--white);
}

.testimonial .name {
  font-size: 0.875rem;
  font-weight: 600;
  color: var(--white);
}

.testimonial .role {
  font-size: 0.8125rem;
  color: var(--gray-400);
}

/* --- Get Involved Section --- */
.involved {
  background: var(--black);
  padding: 120px 24px 80px;
}

.involved-inner {
  max-width: 680px;
  margin: 0 auto;
  text-align: center;
  background: linear-gradient(135deg, rgba(245,197,24,0.06), rgba(245,197,24,0.02));
  border: 1px solid rgba(245,197,24,0.15);
  border-radius: 24px;
  padding: 80px 48px;
}

.involved-inner h2 {
  margin-bottom: 16px;
}

.involved-inner p {
  margin-bottom: 40px;
  max-width: 480px;
  margin-left: auto;
  margin-right: auto;
}

.email-form {
  display: flex;
  gap: 12px;
  max-width: 440px;
  margin: 0 auto 24px;
}

.email-form input {
  flex: 1;
  padding: 14px 20px;
  background: rgba(255,255,255,0.06);
  border: 1px solid rgba(255,255,255,0.12);
  border-radius: 10px;
  color: var(--white);
  font-size: 1rem;
  font-family: var(--font-sans);
  outline: none;
  transition: border-color var(--transition);
}

.email-form input::placeholder {
  color: var(--gray-600);
}

.email-form input:focus {
  border-color: var(--yellow);
}

.email-form button {
  padding: 14px 28px;
  background: var(--yellow);
  color: var(--black);
  font-size: 1rem;
  font-weight: 600;
  border: none;
  border-radius: 10px;
  cursor: pointer;
  font-family: var(--font-sans);
  transition: opacity var(--transition);
  white-space: nowrap;
}

.email-form button:hover {
  opacity: 0.9;
}

.involved-note {
  font-size: 0.8125rem !important;
  color: var(--gray-600) !important;
}

/* --- Footer --- */
.footer {
  border-top: 1px solid rgba(255,255,255,0.06);
  padding: 48px 24px;
}

.footer .container {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.footer-logo {
  font-size: 1rem;
  font-weight: 700;
}

.footer-logo span {
  color: var(--yellow);
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-links a {
  font-size: 0.875rem;
  color: var(--gray-400);
  transition: color var(--transition);
}

.footer-links a:hover {
  color: var(--white);
}

.footer-copy {
  font-size: 0.8125rem;
  color: var(--gray-600);
}

/* --- Animations --- */
.fade-in {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.7s ease-out, transform 0.7s ease-out;
}

.fade-in.visible {
  opacity: 1;
  transform: translateY(0);
}

/* --- Responsive --- */
@media (max-width: 1024px) {
  .why-grid,
  .how-grid,
  .testimonials {
    grid-template-columns: repeat(2, 1fr);
  }

  .stats-row {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --section-padding: 80px 20px;
  }

  .nav-links,
  .nav-cta {
    display: none;
  }

  .nav-toggle {
    display: block;
  }

  .nav-mobile {
    display: flex;
    flex-direction: column;
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: var(--black);
    z-index: 99;
    padding: 100px 32px 40px;
    gap: 8px;
    transform: translateX(100%);
    transition: transform 0.4s cubic-bezier(0.4, 0, 0.2, 1);
  }

  .nav-mobile.open {
    transform: translateX(0);
  }

  .nav-mobile a {
    font-size: 1.5rem;
    font-weight: 600;
    padding: 16px 0;
    color: var(--gray-200);
    border-bottom: 1px solid rgba(255,255,255,0.06);
  }

  .nav-mobile .mobile-cta {
    margin-top: 24px;
    text-align: center;
    padding: 16px;
    background: var(--yellow);
    color: var(--black);
    border-radius: 10px;
    font-weight: 600;
    border: none;
  }

  .what .container {
    grid-template-columns: 1fr;
    gap: 48px;
  }

  .what-visual {
    grid-template-columns: 1fr 1fr;
  }

  .why-grid,
  .how-grid {
    grid-template-columns: 1fr;
  }

  .testimonials {
    grid-template-columns: 1fr;
  }

  .stats-row {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .hero {
    padding: 140px 20px 100px;
  }

  .hero-scroll {
    display: none;
  }

  .email-form {
    flex-direction: column;
  }

  .involved-inner {
    padding: 48px 24px;
  }

  .footer .container {
    flex-direction: column;
    gap: 20px;
    text-align: center;
  }
}

@media (max-width: 480px) {
  .what-visual {
    grid-template-columns: 1fr;
  }

  .who-tags {
    gap: 8px;
  }

  .who-tag {
    padding: 10px 20px;
    font-size: 0.875rem;
  }
}